Piston skirt expander



A. W. WE NZEL PISTON SKIRT EXPANDER Nov. 24, 1936.

Filed Nov. 2, 1935 Patented Nov. 24, 1936 UNITED STATES PATENT OFFICE 4 Claims.

My invention relates to new and useful improvements in piston skirt expanders, and has for an object to provide a means for efliciently expanding the skirts of new or worn pistons. If

new pistons are to be used in slightly worn cylinders, it is desirable that "the skirt be expanded. Also, old or slightly worn pistons have a tendency to piston slap, and if the skirt is expanded, this, in a good many instances, will be overcome.

One of the principal objects of the invention is to provide a piston skirt expander comprising substantially a properly tempered spring wire element having two arms and-an eyelet or loop formed integral therewith, so that the arms may be fitted into one portion of the split skirt and the loop or eyelet secured to the opposite (adjacent) portion of the skirt. Thus, there will be a spreading action provided which, although relatively light, will tend to spread the skirts an additional five to twenty ten-thousandths which usually is sulficlent to prevent the objectionable slapping of the piston.

Still another object of the invention is to provide a piston skirt expander, preferably made of one piece of wire which is bent to provide two arms with offset ends and also bent to provide an integral eyelet, the latter spaced centrally of the arms and to the rear thereof, as shown in the preferred form. Again, the expander may be formed by bending the arms inwardly and then in an offset plane to form aretainingloop, as shown in one of the modifications. Further, the expander may comprise asingle piece of wire bent with a double'curve centrally of its length and then outwardly toward the opposite ends to form two diverging arms, as shown in another modification.

Still another object of the invention is to provide'an especially resilient form of skirt expander and to also provide a very efficient means for holding the expander in position. In either the preferred or the modified forms, the central portion of the expander, that is, either the loop or the eyelet or the double curve, is secured to" one portion of the split skirt, while the ends of the resilient arms are fastened in the other portion of the split skirt, thus providing the desired spreading action at all times.

, 'In the drawing showing a preferred embodiment and two, slight modifications,

Fig. 1 is a detailed elevation of the preferred form of piston skirt expander, showing a piece ofv wire bent to form the two arms and an integral eyelet;

Fig. 2 is a front end view of the same;

Fig. 3 is a side elevation, partly in section, of

I a piston showing the skirt expander secured ,in

position, the arms being also shown in dotted lines'in the position which they will assume be- 0 fore being retained in their receiving apertures;

skirt pistons.

Fig. 4 is a detailed sectional view taken on the line 6-4 of Fig. 3; 4

Fig. 5 is an end view of a slightly modified form of piston skirt expander;

Fig. 6 is a View similar to Fig. 3, showing the 5 'manner of retaining the expander shown in Fig.

5 in position;

Fig. 7 is a sectional view taken on the line of Fig. 6; and

Fig. 8 is a fragmentary detailed view of a fur- 10 ther modification of the expander and the means for holding the same in position.

Referring now more particularly to the several views, and to Fig. 3 for the moment, there is shown a piston block I, comprising the head por- 15 tion 2, with the annular grooves 3 for the reception of the piston rings and oil rings. There may also be seenthe skirt 4 with the bearings 5 therein for the reception of the wrist pin of a connecting rod (not shown), and it will be noticed 20 that the skirt is split, there being the Vertically extending slot 6. I

It will be understood that I do not wish to be limited to the specific manner in which the skirt is split, as these pistonskirt expanders may be 25 very efificiently used with various forms of split Having referred briefly to the piston, reference is now made to the skirt expander per se. Referring to Fig. l,there is shown a preferred 30 i type of expander, made from resilient wire, which, after being 'bent to form, is properly hardened and tempered. It will be seen that it consists of one piece or. section of wire which is bent to form the arcuate arm ,1 and the correspond- 35 ingly bent arcuate arm 8, the arms being then twisted about each other, as at 9, and then bent to form the eye or eyelet I0. The outer ends ll of the arms I and 8 are then-bent at right angles to the plane of the open-face eyelet, as 40 .may be seen in Fig.2.

. opposite from these apertures in the other portion of the skirt, that is, on the opposite side of the slot 6, there is also drilled an opening or aperture l2 to receive the barrel l2 of the stud S. This aperture l2 should provide what is technically known as a drive fit for the pin or barrel I! of the stud.

After the stud is positioned within its aperture, the end of the stud may be peened or headed, but care should be taken that the stud does not extend beyond the outer surface of the piston wall, as if this were so, it would tend to score the cylinder.

To apply the piston expander, therefore, it will be seen that the eyelet I will be placed over the aperture l2 within the piston and the stud then driven or riveted in place, thus tightly securing the expander in position.

After this, the arms II will be pulled toward the eyelet until the ends ll snap within the apertures II which, it will be remembered, are on the opposite side of the slot 6.

Thus, it will be seen that there will always be a spreading action caused by this piston expander, the two arms tending to force one portion of the skirt away from the portion to which the eyelet is attached. I

Should it so happen that the piston skirt expander break, it is but the matter of a moment to drive out the stud and rivet a new one in position.

It will also be seen that by forming a piston skirt expander in this manner, that is, by twisting or intertwining the arms, at 9, there is less likelihood of the two arms I and 8 snapping or breaking, as there are no sharp bends to fatigue the metal during the formation of the expander.

Referring now to a slightly modified form, and to Figs. 5 to '7, inclusive, there is also shown a piston block I 5 with its skirt l6, bearings l1, and the vertical slot la in the skirt. There is further shown a wire piston skirt expander l9,

1 and in this instance the expander has the diverging arms and 2| with the outer ends 22 extending in a horizontal plane therefrom, the arms 20 and 2| at their inner ends extending transversely and merging in the offset loop or bend 23.

Now to position this expander, a small recess 24 (see Fig. 7) is cut in the inner surface of" than drilling a hole or aperture, as shown at I2 in the preferred form. However, the expander with its fastening means of this species has proved very efficient .in action.

Referring to a still further slightly modified form, there is shown in Fig. 8 the fragmentary portion 21 of a skirt, the slot 28, a plain stud 29, the two apertures 30, and'the wire skirt expander 3|.

In this instance, the expander 3| has the two outwardly extending arms 32, which diverge from the arcuate central portion 33, which latter portion bears, in turn, against the heretofore men tioned stud 29. The central portion is substantially in the form of an ogee curve, so that there are no sharp bends to fatiguethe metal.

The outer ends of the arms 32 will also be offset, as shown in the other forms, to be received in the two apertures 30.

It might be mentioned that the slots in the piston skirts, that is, the slot 6, as shown in Fig. 3, the slot It, as shown in Fig. 6, or the slot 28, shown in Fig. 8, have recesses. 34 formed v therein near their upper and lower ends, in which the respectivespring arms may be sprung if it is desired to put a greater tension thereon'to thus more effectively separate theskirts of the piston. 1 7

It will also be understood that the respective apertures H, 22, and 30 are not always absolutely necessary, as the apertures 34 may be used. However, I have found it expedient to have these separate apertures in case it is not desired to have as great a tension on the arms as if they were sprung into the respective apertures 34.

As heretofore mentioned, these expanders are all made on jigs and then properly hardened and tempered to provide the desired resiliency.

From the foregoing, it will be seen that I have designed a piston skirt expander that will overcome the objectionable piston slapping and that I have also devised means for securely holding the same in place, so that there is no probability of their springing from their set position.

Furthermore, by constructing these expanders from one piece of wire and bending them in the manner shown, any danger of fatiguing the metal during their formation is avoided.

It will be understood that I do not wish to be limited to the identical shape of the arms or .necessarily to the number of arms used.

I am aware that it is old to provide piston skirt expanders of U-shape and other forms and am not claiming my invention as such, but what I do claim as new and desire to secure by Letters Patent is:

1. A piston expander for a slotted piston having skirt portions one of which is apertured, comprising a spring member having a looped central portion and similar diverging arms extending from the loopedcentral portion, the ends of the arms being offset, said looped central portion being adapted to be fastened to one skirt portion of the piston with the offset ends of the arms adapted to be fitted within the apertures of the other skirt portion.

2. An expander for a slotted piston skirt comprising an eyelet portion formed of spring wire, two similar diverging integral arms twisted about each other adjacent the eyelet merging therewith and extending in opposite directions,'and lugs on the ends of the arms at right angles to the open face of the eyelet.

3. An expander for a slotted pistonskirt consisting of a spring member bent centrally to form an eyelet, arms twisted at their inner ends about and havinglugs on their ends extending at right angles to the open faces of the eyelet. v

4. A piston expander comprising a single. strand of resilient wire provided with an attaching loop centrally thereof, a pair of similar arms diverging frcam the loop, said arms provided with offset en 5.

each other and merging with the eyelet, said arms being curved and diverging from the twisted ends ALBERT w. WENZEL. 

